Hubble Space Telescope Operations Control Center (STOCC)

The Hubble Space Telescope is kept under a watchful
eye by a dedicated team of professionals at NASA Goddard Space Flight
Center’s Telescope
Operations Control Center, or STOCC.

This group is called the Flight Operations Team (FOT)
and is comprised of Hubble engineers and managers who work seven days
a week, 365 days a year, constantly monitoring the telescope’s
operations.

The STOCC consists of three conjoined rooms:

In the Mission
Operations Room the FOT closely monitors
the telescope’s health and safety, as well as controlling flight
operations. Some of the tasks they perform include in-depth subsystem
analysis, simulated subsystem tests, integrating new databases, and
validating new ground software and updates to flight software.

Shortly
before the Hubble servicing mission in 2008, additional engineers
from the subsystems engineering group will be called upon to staff
the Servicing
Mission Operations Room. This Servicing Mission Operations
Team (SMOT) will work in two 12-hour shifts, supporting the preparation,
test and simulation for the fifth and final shuttle mission to the
famed telescope.

Preparing Hubble for Servicing

Just as NASA astronauts train extensively for each shuttle mission,
so do the SMOT and FOT engineers. Their highly choreographed efforts
and expertise help ensure the servicing mission goes as planned.

A few hours after the Shuttle Atlantis lifts off
from Kennedy Space Center, the FOT will prepare the telescope for servicing
by placing its science instruments into ‘safe hold.’ During
this time, engineers will track Hubble and downlink necessary engineering
data.

About 28 hours into the servicing mission, the team
will command Hubble to close its aperture door to protect its ultra-sensitive
optics. Then the team will send commands to the telescope so it obtains
the required rendezvous attitude (for grappling by the shuttle arm),
stows, or retracts, its high gain antennas, and repositions its solar
arrays to enable the shuttle arm to grapple the telescope.

The astronauts will then secure the telescope to
the shuttle’s
Flight Support System, which will allow them to reach all the instruments
and components slated for repair or replacement. Hubble’s internal
power will be transferred to the shuttle during servicing.

Testing Hubble during Servicing

During the servicing mission, the SMOT engineers
will performaliveness and functionaltests to ensure each instrument
and component has power and operates as it should. While the astronauts’ sleep,
this same team will conduct additional functional tests on each installed
component to determine if the astronauts need to perform additional work.

After all tasks are completed, astronauts will attach
the grapple arm to Hubble and charge its newly installed battery packs.
After the batteries are fully charged, power will be transferred from
the shuttle to the telescope’s internal power and the power feed
will be disconnected.

The FOT engineers will send commands to Hubble to
open its aperture door and the telescope will be released. Additional
commands will be sent to deploy Hubble’s high gain antennas and
after orbital verification is completed, Hubble will be re-commissioned
for future science observations.

The FOT engineers upload these approved observing
schedules to the telescope via a network interface to NASA’s
White Sands Complex in New Mexico, which then transmits to NASA’s
Tracking and Data Relay Satellite System for uplink to Hubble. Conversely,
scientific data obtained by Hubble are sent back to the STOCC by reverse
path, and forwarded to the Space Telescope Science Institute via dedicated
high-speed links.

Since the Tracking and Data Relay Satellite System supports several
orbiting spacecraft, all commands and returning data are carefully choreographed. Due
to the potential for limited availability, Hubble’s command sequences
are up-linked periodically and stored in the telescope’s onboard
computer. Hubble then executes the observations automatically at pre-scheduled
times.

The final shuttle servicing mission to Hubble will enable the telescope
to continue producing world-class science for five years or longer and
could overlap observations performed by NASA’s James Webb Space
Telescope, scheduled for launch in 2013.